Yale Environment 360: Measurements of global forest cover can vary widely by as much as 6 percent of the planet's land area, a swath equal in size to China, according to research from the University of Maryland. The reason behind the discrepancy actually lies in how different researchers and organizations define forest cover, the researchers note. Geographers have long called for the definition to be standardized, but until now, no one had quantified the scope of the variance. The largest ambiguities in forest calculations...